Positive Pressure Application; Sealing Air - B-I Inductrial BI-SM2004 Manual

B-I INDUSTRIAL CO., LTD.
SMOKE DENSITY INDICATOR
3-2-9 Positive Pressure Applications
On oil fired boilers a pressure wave may be caused when the burner ignites disturbing soot
accumulations and depositing them on the lenses. Therefore, the units should be located as
far as possible from the actual flue gas outlet of the boiler. Injecting clean air is not always
effective as the momentary pressure can be severe. Accordingly, it is important to observe
this precaution even when injected clean air is used during normal running conditions.
Installation details of sealing air
☞. Sealing Air
To minimise sooting-up of the lenses during normal operation, air pressurised above the
stack pressure should be fed via copper tubing into the PF1/4 inch BSP tapping provided on
each unit. The air supply should be switched on before the boiler is fired and should not be
switched off until after the firing sequence has shut down and the purge cycle is complete.
Air supply may be a compressed air line, Blower unit or from a boiler FD fan illustrated above.
Purge air pressure must exceed duct or flue pressure.
Air Pressure : 0.3 ~ 1.0 kg/㎠